Sliding gate valves are well known in the steel-making industry for controlling the flow of molten steel. These types of valves, however, are not used in the processing relatively low melting temperature metals, such as aluminum or zinc, due to the valves becoming clogged and jammed by solid contaminants or dross found in the molten metal bath. Cleaning or repairing the contaminants from the valve would be too time-consuming and expensive. There is therefore a need for an improved sliding gate valve that will operate immersed in a molten metal bath of aluminum, while preventing dross accumulation or build-up.
A typical molten metal facility includes a furnace with one or more pumps for moving molten metal. During the processing of molten metals, such as aluminum, the molten metal is normally continuously circulated through the furnace by a centrifugal impeller pump, i.e., a circulation pump, to equalize the temperature of the molten bath. A typical furnace includes a pump well that is located between the heating chamber or hearth and the charge well (where raw material is inserted into the furnace). These three main sections of a typical furnace are fluidly interconnected with the circulation pump causing the molten metal to circulate from the pump well to the charge well to the hearth and back into the pump well.
To transfer the molten metal out of the furnace, typically for casting the metal, a second transfer pump is used to elevate the metal up through a discharge conduit that runs up and out of the furnace.
The pump well typically includes the circulation pump and, if there is enough space, the separate transfer pump. If there is not enough room in a particular furnace's pump well, the circulation pump must be removed and replaced with the transfer pump when retrieving/pouring molten metal from the furnace.
While the current two pump system is effective for its intended purpose, purchasing and maintaining two separate pumps is expensive and inefficient, particularly when the two pumps must be swapped out in smaller pump wells. There is therefore a need for a device that can be immersed in a bath of molten metal that can selectively redirect the output from a single pump from the circulation of the metal within the furnace to transferring the metal out of the furnace.